Full liquid-product air separation equipment and process therefor

ABSTRACT

A full liquid-product air separation equipment is disclosed. The equipment comprises an air filtration system, a compression system, a precooling system, a purification system, a high-temperature expander having a first pressurizing part and a first expanding part, a low-temperature expander having a second pressurizing part and a second expanding part, a main heat exchanger having a first heat exchange pipeline, a second heat exchange pipeline, a third heat exchange pipeline, a fourth heat exchange pipeline and a fifth heat exchange pipeline, and a rectification system for rectifying air. The equipment has a simple configuration, is easy to implement, and has high gas separation efficiency and low energy consumption.

TECHNICAL FIELD

The present disclosure belongs to the field of air separation technology (technology for separating various components from air), and specifically relates to a full liquid-product air separation equipment and process therefor.

BACKGROUND

In the existing air separation equipment and associated process, numerous compressors are usually used for refrigeration and air circulation, and refrigeration equipments are usually required to provide cold energy, which has shortcomings of low efficiency and high energy consumption.

SUMMARY

The present disclosure provides a full liquid-product air separation equipment with higher efficiency and lower energy consumption.

A full liquid-product air separation equipment comprises:

an air filtration system;

a compression system;

a precooling system;

a purification system;

a high-temperature expander, having a first pressurizing part and a first expanding part;

a low-temperature expander, having a second pressurizing part and a second expanding part;

a main heat exchanger, having a first heat exchange pipeline, a second heat exchange pipeline, a third heat exchange pipeline, a fourth heat exchange pipeline and a fifth heat exchange pipeline; and

a rectification system for rectifying air;

wherein the air filtration system, the compression system, the precooling system, and the purification system are connected sequentially and then connected to the first pressurizing part, and the first pressurizing part is connected to the second pressurizing part connected to the first heat exchange pipeline;

the first heat exchange pipeline comprises a main pipeline connected to the second pressurizing part and two first branches connected to the main pipeline, one of the two first branches is connected to the second expanding part and the other of the two first branches is connected to the rectification system;

the second expanding part is connected to the second heat exchange pipeline and the rectification system, respectively, a waste nitrogen pipeline connected to the rectification system for extracting a stream of pressure waste nitrogen is connected to the second heat exchange pipeline, the second exchange pipeline is connected to the first expanding part, and the first expanding part is connected to the third heat exchange pipeline;

the third heat exchange pipeline has two second branches, one of the two second branches is connected to the purification system to provide adsorbent regeneration gas, and the other of the two branches is connected to the precooling system; and the rectification system has a low-pressure waste nitrogen outlet connected to the fourth heat exchange pipeline, and the low-pressure nitrogen outlet is connected to the fifth heat exchange pipeline, and the fourth and fifth heat exchange pipelines are both connected to the precooling system.

Another aspect of the present disclosure provides a process for full liquid-product air separation using the above-mentioned full liquid-product air separation equipment, comprising:

filtering, compressing, precooling and purifying air;

continuously pressurizing the air through the first pressurizing part of the high-temperature expander and the second pressurizing part of the low-temperature expander, then exchanging heat in the first heat exchange pipeline of the main heat exchanger, extracting a part of the air in the first heat exchange pipeline in a middle portion thereof and expanding in the second expanding part of the low-temperature expander, and making a high-pressure liquid air formed by the other part of the air at a bottom of the main heat exchanger enter the rectification system;

dividing the air expanded by the second expanding part into two parts to enter the second heat exchange pipeline of the main heat exchanger and the rectification system for distillation, respectively;

extracting a stream of pressure waste nitrogen from the rectification system to merge into the second heat exchange pipeline, mixing the waste nitrogen and exchanging heat through the second heat exchange pipeline, and then expanding it in the first expanding part of the high-temperature expander into a low-pressure waste nitrogen, reheating the low-pressure waste nitrogen through the third heat exchange pipeline of the main heat exchanger into a low-pressure room-temperature waste nitrogen;

a part of the low-pressure room-temperature waste nitrogen entering the purification system to provide an adsorbent regeneration gas for the purification system, and the other part of the low-pressure room-temperature waste nitrogen entering the precooling system;

reheating the low-pressure waste nitrogen generated by the rectification system through the fourth heat exchange pipeline of the main heat exchanger, reheating the low-pressure nitrogen generated by the rectification system through the fifth heat exchange pipeline of the main heat exchanger; and

letting the waste nitrogen reheated through the fourth heat exchange pipeline and the nitrogen reheated through the fifth heat exchange pipeline both enter the precooling system.

In an embodiment, the air is filtered, compressed, precooled, and purified to remove water and carbon dioxide into purified and compressed air with a pressure of 10-60 bar and a temperature of 5-50° C.

In an embodiment, the air enters a medium-pressure purification system to remove water and carbon dioxide.

In an embodiment, the high-pressure liquid air enters the rectification system after throttling.

In an embodiment, the air entering in the rectification system is separated and liquidized to obtain liquid nitrogen, liquid oxygen and liquid argon.

The present disclosure has the following advantages over the prior art: the present disclosure has a simple configuration, is convenient to implement, and provides high air separation efficiency, high oxygen extraction rate, and has low energy consumption.

BRIEF DESCRIPTION

FIG. 1 is a process flow diagram of the full liquid-product air separation equipment of an embodiment of the present disclosure.

REFERENCE NUMBER

1—pretreatment system (including an air filtration system, a compression system, a precooling system and a purification system); 2—high-temperature expander; 21—first expanding part; 22—first pressurizing part; 3—low-temperature expander; 31—second expanding part; 32—second pressurizing part; 4—main heat exchanger; 5—rectification system; 6—first heat exchange pipeline; 7—second heat exchange pipeline; 8—third heat exchange pipeline; 9—fourth heat exchange pipeline; 10—fifth heat exchange pipeline; 11—main pipeline; 12—first branch; 13—first branch; 14—waste nitrogen pipeline.

DETAILED DESCRIPTION

In the following, the present disclosure is further described combining with embodiments shown in the accompanying drawings.

As shown in FIG. 1 , a kind of full liquid-product air separation equipment comprises a pretreatment system 1, a high-temperature expander 2, a low-temperature expander 3, a main heat exchanger 4, and a rectification system 5 for distilling air. The expanders, including the high-temperature expander 2 and the low-temperature expander 3, all have an expanding part for expanding a gas to depressurize and a pressurizing part for compressing the gas to pressurize, that is, the high-temperature expander 2 has a first expanding part 21 and a first pressurizing part 22, and the low temperature expander 3 has a second expanding part 31 and a second pressurizing part 32.

The pretreatment system 1 comprising an air filtration system, a compression system, a precooling system, and a purification system connected sequentially is connected to the first pressurizing part 22, the first pressurizing part 22 is connected to the second pressurizing part 32, the second pressurizing part 32 is connected to a first heat exchange pipeline 6 of the main heat exchanger 4, the first heat exchange pipeline 6 of the main heat exchanger 4 comprises a main pipeline 11 connected to the second pressurizing part 32 and two first branches 12, 13 branching off from the main pipeline 11, wherein one first branch 12 is connected to the second expanding part 31, and the other first branch 13 is connected to the rectification system 5. The second expanding part 31 is divided into two branches which are respectively connected to a second heat exchange pipeline 7 of the main heat exchanger 4 and the rectification system 5, a waste nitrogen pipeline 14 connected to the rectification system for extracting a stream of pressure waste nitrogen is merged into the second heat exchange pipeline 7 of the main heat exchanger 4. The second exchange pipeline 7 of the main heat exchanger 4 is connected to the first expanding part 21, and the pressure waste nitrogen is expanded through the high-temperature expander 2 into low-pressure waste nitrogen. The first expanding part 21 is then connected to a third heat exchange pipeline 8 of the main heat exchanger 4, an outlet of the third heat exchange pipeline 8 of the main heat exchanger 4 is divided into two second branches, one second branch is connected to the purification system to provide adsorbent regeneration gas, and the other second branch is connected to the precooling system. That is, the low-pressure waste nitrogen is reheated into low-pressure room-temperature waste nitrogen by the third heat exchange pipeline 8 of the main heat exchanger 4, a part of which enters the purification system to provide adsorbent regeneration gas for the purification system, and the other part of which is connected to the precooling system to participate in the production of chilled water. The low-pressure waste nitrogen outlet of the rectification system 5 is connected to a fourth heat exchange pipeline 9 of the main heat exchanger 4, and a low-pressure nitrogen outlet of the rectification system 5 is connected to a fifth heat exchange pipeline 10 of the main heat exchanger 4, and the fourth heat exchange pipeline 9 and the fifth heat exchange pipeline 10 of the main heat exchanger 4 are both connected to the precooling system.

In a process for full liquid-product air separation based on the above-mentioned full liquid-product air separation equipment, air is filtered, compressed, precooled, and purified to remove water and carbon dioxide into purified and compressed air with a pressure of 10-60 bar and a temperature of 5-50° C. The purified and compressed air is continuously pressurized through the first pressurizing part 22 and the second pressurizing part 32, and enters the first heat exchange pipeline 6 of the main heat exchanger 4, wherein a part of the air in the first heat exchange pipeline 6 of the main heat exchanger 4 is extracted in the middle portion of the main heat exchanger 4 and enters the second expanding part 31 for expansion, and the other part of the air becomes high-pressure liquid air at the bottom of the main heat exchanger 4 and enters the rectification system 5. The air expanded by the second expanding part 31 is divided into two branches, one enters the second heat exchange pipeline 7 of the main heat exchanger 4 for heat exchange and the other one enters the rectification system 5 for distillation. A stream of pressure waste nitrogen is extracted by the rectification system 5 and is merged into the second heat exchange pipeline 7 of the main heat exchanger 4, the waste nitrogen after mixing and exchanging heat through the second exchange pipeline 7 of the main heat exchanger 4 enters the first expanding part 31 and is expanded into low-pressure waste nitrogen, and the low-pressure waste nitrogen is reheated through the third heat exchange pipeline 8 of the main heat exchanger into low-pressure room-temperature waste nitrogen. A part of the low-pressure room-temperature waste nitrogen enters the purification system to provide adsorbent regeneration gas for the purification system, and the other part thereof enters the precooling system to participate in the production of chilled water. The rectification system performs separation and liquefaction to obtain liquid nitrogen, liquid oxygen and liquid argon, and generate low-pressure waste nitrogen and low-pressure nitrogen. The low-pressure waste nitrogen generated by the rectification system 5 is reheated through the fourth heat exchange pipeline 9 of the main heat exchanger 4, and the low-pressure nitrogen generated by the rectification system 5 is reheated through the fifth heat exchange pipeline 10 of the main heat exchanger 4, and the waste nitrogen reheated through the fourth heat exchange pipeline 9 of the main heat exchanger 4 and the low-pressure nitrogen reheated through the fifth heat exchange pipeline 10 of the main heat exchanger 4 both enter the precooling system to produce chilled water.

After filtering, compression, precooling and purification, compressed air enters the first and second pressurizing parts of the high-temperature expander 2 and the low-temperature expander 3 for continuous pressurization, and enters the main heat exchanger 4 for heat exchange, then the air is expanded through the low-temperature expander 3, mixed with pressure waste nitrogen in the main heat exchanger 4 and reheated, and then enters the high-temperature expander 2 for expansion, and is reheated in the main heat exchanger 4 into low-pressure room-temperature waste nitrogen, that is, the high-temperature expander 2 and the low-temperature expander 3 use the principle of high temperature and high enthalpy to perform high-efficiency expansion refrigeration under the condition of high pressure and high temperature.

The embodiments described above are only for illustrating the technical concepts and features of the present disclosure, and are intended to make those skilled in the art being able to understand the present disclosure and thereby implement it, and should not be concluded to limit the protective scope of this disclosure. 

What is claimed is:
 1. A full liquid-product air separation equipment comprising: an air filtration system; a compression system; a precooling system; a purification system; a high-temperature expander, having a first pressurizing part and a first expanding part; a low-temperature expander, having a second pressurizing part and a second expanding part; a main heat exchanger, having a first heat exchange pipeline, a second heat exchange pipeline, a third heat exchange pipeline, a fourth heat exchange pipeline and a fifth heat exchange pipeline; and a rectification system for rectifying air; wherein the air filtration system, the compression system, the precooling system, and the purification system are connected sequentially and then connected to the first pressurizing part, and the first pressurizing part is connected to the second pressurizing part connected to the first heat exchange pipeline; the first heat exchange pipeline comprises a main pipeline connected to the second pressurizing part and two first branches connected to the main pipeline, one of the two first branches is connected to the second expanding part and the other of the two first branches is connected to the rectification system; the second expanding part is connected to the second heat exchange pipeline and the rectification system, respectively, a waste nitrogen pipeline connected to the rectification system for extracting a stream of pressure waste nitrogen is connected to the second heat exchange pipeline, the second exchange pipeline is connected to the first expanding part, and the first expanding part is connected to the third heat exchange pipeline; the third heat exchange pipeline has two second branches, one of the two second branches is connected to the purification system to provide adsorbent regeneration gas, and the other of the two branches is connected to the precooling system; and the rectification system has a low-pressure waste nitrogen outlet connected to the fourth heat exchange pipeline, and the low-pressure nitrogen outlet is connected to the fifth heat exchange pipeline, and the fourth and fifth heat exchange pipelines are both connected to the precooling system.
 2. A process for full liquid-product air separation, using the full liquid-product air separation equipment according to claim 1, comprising: filtering, compressing, precooling and purifying air to remove water and carbon dioxide into purified and compressed air with a pressure of 10-60 bar and a temperature of 5-50° C.; continuously pressurizing the purified and compressed air through the first pressurizing part of the high-temperature expander and the second pressurizing part of the low-temperature expander, then exchanging heat in the first heat exchange pipeline of the main heat exchanger, extracting a part of the air in the first heat exchange pipeline in a middle portion thereof and expanding in the second expanding part of the low-temperature expander, and making a high-pressure liquid air formed by the other part of the air at a bottom of the main heat exchanger enter the rectification system after throttling; dividing the air expanded by the second expanding part into two parts to enter the second heat exchange pipeline of the main heat exchanger and the rectification system for distillation, respectively; extracting a stream of pressure waste nitrogen from the rectification system to merge into the second heat exchange pipeline, mixing the waste nitrogen and exchanging heat through the second heat exchange pipeline, and then expanding it in the first expanding part of the high-temperature expander into a low-pressure waste nitrogen, reheating the low-pressure waste nitrogen through the third heat exchange pipeline of the main heat exchanger into a low-pressure room-temperature waste nitrogen; a part of the low-pressure room-temperature waste nitrogen entering the purification system to provide an adsorbent regeneration gas for the purification system, and the other part of the low-pressure room-temperature waste nitrogen entering the precooling system to produce chilled water; separating and liquidizing the air entering the rectification system to produce liquid nitrogen, liquid oxygen and liquid argon; reheating the low-pressure waste nitrogen generated by the rectification system through the fourth heat exchange pipeline of the main heat exchanger, reheating the low-pressure nitrogen generated by the rectification system through the fifth heat exchange pipeline of the main heat exchanger; and letting the waste nitrogen reheated through the fourth heat exchange pipeline and the nitrogen reheated through the fifth heat exchange pipeline both enter the precooling system to produce chilled water.
 3. A process for full liquid-product air separation, using the full liquid-product air separation equipment according to claim 1, comprising: filtering, compressing, precooling and purifying air; continuously pressurizing the air through the first pressurizing part of the high-temperature expander and the second pressurizing part of the low-temperature expander, then exchanging heat in the first heat exchange pipeline of the main heat exchanger, extracting a part of the air in the first heat exchange pipeline in a middle portion thereof and expanding in the second expanding part of the low-temperature expander, and making a high-pressure liquid air formed by the other part of the air at a bottom of the main heat exchanger enter the rectification system; dividing the air expanded by the second expanding part into two parts to enter the second heat exchange pipeline of the main heat exchanger and the rectification system for distillation, respectively; extracting a stream of pressure waste nitrogen from the rectification system to merge into the second heat exchange pipeline, mixing the waste nitrogen and exchanging heat through the second heat exchange pipeline, and then expanding it in the first expanding part of the high-temperature expander into a low-pressure waste nitrogen, reheating the low-pressure waste nitrogen through the third heat exchange pipeline of the main heat exchanger into a low-pressure room-temperature waste nitrogen; a part of the low-pressure room-temperature waste nitrogen entering the purification system to provide an adsorbent regeneration gas for the purification system, and the other part of the low-pressure room-temperature waste nitrogen entering the precooling system; reheating the low-pressure waste nitrogen generated by the rectification system through the fourth heat exchange pipeline of the main heat exchanger, reheating the low-pressure nitrogen generated by the rectification system through the fifth heat exchange pipeline of the main heat exchanger; and letting the waste nitrogen reheated through the fourth heat exchange pipeline and the nitrogen reheated through the fifth heat exchange pipeline both enter the precooling system.
 4. The process for full liquid-product air separation according to claim 3, wherein the air is filtered, compressed, precooled, and purified to remove water and carbon dioxide into purified and compressed air with a pressure of 10-60 bar and a temperature of 5-50° C.
 5. The process for full liquid-product air separation according to claim 3, wherein the high-pressure liquid air enters the rectification system after throttling.
 6. The process for full liquid-product air separation according to claim 3, wherein the air entering in the rectification system is separated and liquidized to obtain liquid nitrogen, liquid oxygen and liquid argon. 